web services

04/10/23 Distributed Computing, M. L. Liu 1

Web Services

M. L. Liu


Sources of InformationProgramming Web Services with SOAP, by Snell et al, O’ReillySOAP Tutorial, http://www.w3schools.com/soap/default.aspSoapRPC.com: Tutorials, (http://www.soaprpc.com/tutorials/) A Busy Developer’s Guide To Soap1.1DaveNet : XML-RPC for Newbies, http://davenet.userland.com/1998/07/14/xmlRpcForNewbiesSoapRPC.com: Other resources, http://www.soaprpc.com/resources/


Web ServicesNetwork services provided over HTTP – “wired services”It is promoted as a new way to build network applications from distributed components that are language- and platform-independentThe technologies are still evolvingWe are more interested in the concept and principles, but we will look into one API (Apache SOAP).


Web Services

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Web Service Software Components

A web service is a message-based network service.

A server which provides a web service must be capable of “sending and receiving messages using some combination of standard Internet protocols”

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Just-in-time integration

Network services can be integrated dynamically, on an as-needed basis.

SunMicro’s jini is a framework that supports the idea.

Network services are registered with a service registry; a service consumer/client looks up the registry to fulfill its needs.

The binding of a client to the service can occur at runtime.


Web service protocol stack

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Web service protocols

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UD D I (Un iv e rs a l D e s cript io n , D is co v e ry , a n d I n te g ra t io n )

W S D L (W e b S e rv ice D e s cript io n L a n g u a g e )

X M L , S O A P (S im ple O bje ct A cce s s Pro to co l)

TC P, H TTP, S M TP, J a bbe r

I P


SOAP

SOAP is a protocol which applies XML for message exchange in support of remote method calls over the Internet.

Compared to remote method invocation or CORBA-based facilities: – SOAP is web-based or “wired” and hence is not

subject to firewall restrictions– Language-independent– Can provide just-in-time service integration


Remote Procedure Call using HTTP

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SOAP Messages

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An XML-encoded SOAP RPC

< s o a p:En v e lo pe x m ln s : s o a p= 'h t tp: //www.w3 .o rg /2 0 0 1 /1 0 /s o a p-e n v e lo pe '> < s o a p:H e a de r>

< - - H e a de rs g o h e re - ->

< /s o a p:H e a de r> < s o a p:B o dy >

< - - R e qu e s t g o e s h e re - ->

< /s o a p:B o dy >< /s o a p:En v e lo pe >

S o u rce : h t tp: //www.x m l.co m /


Example of a SOAP message

< s o a p:En v e lo pe x m ln s : s o a p= 'h t tp: //www.w3 .o rg /2 0 0 1 /1 0 /s o a p-e n v e lo pe '>< s o a p:H e a de r>

< h :L o g x m ln s :h = 'h t tp: //e x a m ple .o rg /cv s /lo g g in g '> < tra ce > 4 < /tra ce > < /h :L o g > < h : PS e rv e r x m ln s :h = 'h t tp: //e x a m ple .o rg /cv s /ps e rv e r' s o a p: m u s tUn de rs ta n d= 'tru e ' > < u s e rn a m e > a n o n cv s @ e x a m ple .o rg < /u s e rn a m e > < pa s s wo rd> a n o n cv s < /pa s s wo rd> < /h : PS e rv e r> < /s o a p:H e a de r>

< s o a p:B o dy > < m :C h e ck o u t x m ln s :m = 'h t tp: //e x a m ple .o rg /cv s '> < s o u rce > /x m l/s o a p/we bs e rv ice s /cv s < /s o u rce > < re v is io n > 1 .1 < /re v is io n > < de s t in a t io n > /e tc/u s r/m a rt in g /s o u rce /x m l< /de s t in a t io n > < /m :C h e ck o u t> < /s o a p:B o dy >< /s o a p:En v e lo pe >

s o u rce : h t tp: //www.x m l.co m


A SOAP Message that contains a remote procedure call

source: (http://www.soaprpc.com/tutorials/) A Busy Developer’s Guide To Soap1.1

<SOAP-ENV:Envelope SOAP-ENV:encodingStyle= "http://schemas.xmlsoap.org/soap/encoding/" xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/"

xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsd="http://www.w3.org/1999/XMLSchema" xmlns:xsi="http://www.w3.org/1999/XMLSchema-instance">

<SOAP-ENV:Body> <m:getStateName xmlns:m="http://www.soapware.org/"> <statenum xsi:type="xsd:int">41</statenum> </m:getStateName> </SOAP-ENV:Body>

</SOAP-ENV:Envelope>


An Example SOAP Requestsource: (http://www.soaprpc.com/tutorials/) A Busy Developer’s Guide To Soap1.1

< ? x m l v e rs io n = " 1 .0 " ? >< S O A P-ENV :En v e lo pe S O A P- ENV :e n co din g S ty le = " h t tp: //s ch e m a s .x m ls o a p.o rg /s o a p/e n co din g /"x m ln s :S O A P- ENC = " h t tp: //s ch e m a s .x m ls o a p.o rg /s o a p/e n co din g /"x m ln s :S O A P- ENV = " h t tp: //s ch e m a s .x m ls o a p.o rg /s o a p/e n v e lo pe /"x m ln s :x s d= " h t tp: //www.w3 .o rg /1 9 9 9 /X M L S ch e m a "x m ln s :x s i= " h t tp: //www.w3 .o rg /1 9 9 9 /X M L S ch e m a - in s ta n ce " >

< S O A P- ENV :B o dy > < m :g e tS ta te Na m e x m ln s :m = " h t tp: //www.s o a pwa re .o rg /" > < s ta te n u m x s i: ty pe = " x s d: in t" > 4 1 < /s ta te n u m > < /m :g e tS ta te Na m e > < /S O A P- ENV :B o dy > < /S O A P- ENV :En v e lo pe >

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Response example source: (http://www.soaprpc.com/tutorials/) A Busy Developer’s Guide To Soap1.1

< ? x m l v e rs io n = " 1 .0 " ? >< S O A P- ENV :En v e lo pe S O A P- ENV :

e n co din g S ty le = " h t tp: //s ch e m a s .x m ls o a p.o rg /s o a p/e n co din g /"x m ln s :S O A P- ENC = " h t tp: //s ch e m a s .x m ls o a p.o rg /s o a p/e n co din g /"x m ln s :S O A P- ENV = " h t tp: //s ch e m a s .x m ls o a p.o rg /s o a p/e n v e lo pe /"x m ln s :x s d= " h t tp: //www.w3 .o rg /1 9 9 9 /X M L S ch e m a "x m ln s :x s i= " h t tp: //www.w3 .o rg /1 9 9 9 /X M L S ch e m a - in s ta n ce " >

< S O A P- ENV :B o dy > < m :g e tS ta te Na m e R e s po n s e x m ln s :m = " h t tp: //www.s o a pwa re .o rg /" > < R e s u lt x s i: ty pe = " x s d:s trin g " > S o u th D a k o ta < /R e s u lt> < /m :g e tS ta te Na m e R e s po n s e > < /S O A P- ENV :B o dy >< /S O A P- ENV :En v e lo pe >

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Example of a SOAP message for an error RPC response

source: (http://www.soaprpc.com/tutorials/) A Busy Developer’s Guide To Soap1.1< ? x m l v e rs io n = " 1 .0 " ? >< S O A P-ENV :En v e lo pe S O A P- ENV :

e n co din g S ty le = " h t tp: //s ch e m a s .x m ls o a p.o rg /s o a p/e n co din g /"x m ln s :S O A P-ENV = " h t tp: //s ch e m a s .x m ls o a p.o rg /s o a p/e n v e lo pe /"x m ln s :x s d= " h t tp: //www.w3 .o rg /1 9 9 9 /X M L S ch e m a "x m ln s :x s i= " h t tp: //www.w3 .o rg /1 9 9 9 /X M L S ch e m a - in s ta n ce " >

< S O A P- ENV :B o dy > < S O A P- ENV :Fa u lt> < fa u lt co de > S O A P- ENV :C lie n t< /fa u lt co de > < fa u lt s t rin g > C a n 't ca ll g e tS ta te Na m e be ca u s e th e re a re t o o m a n y pa ra m e te rs . < /fa u lt s t rin g > < /S O A P- ENV :Fa u lt> < /S O A P- ENV :B o dy >< /S O A P- ENV :En v e lo pe >


HTTP and SOAP RPC Requestsource: (http://www.soaprpc.com/tutorials/) A Busy Developer’s Guide To Soap1.1

A SOAP message can be used to transport a SOAP remote procedure request/response, as follows: POST /examples HTTP/1.1

User-Agent: Radio UserLand/7.0 (WinNT)Host: localhost:81Content-Type: text/xml; charset=utf-8Content-length: 474SOAPAction: "/examples"<blank line>

<text for SOAP message>


An HTTP request that carries a SOAP RPC request source: (http://www.soaprpc.com/tutorials/) A Busy Developer’s Guide To Soap1.1

POST /examples HTTP/1.1User-Agent: Radio UserLand/7.0 (WinNT)Host: localhost:81Content-Type: text/xml; charset=utf-8Content-length: 474SOAPAction: "/examples"

<?xml version="1.0"?><SOAP-ENV:Envelope SOAP-ENV:encodingStyle=

"http://schemas.xmlsoap.org/soap/encoding/" xmlns: SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/" xmlns: SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"

xmlns:xsd="http://www.w3.org/1999/XMLSchema" xmlns:xsi="http://www.w3.org/1999/XMLSchema-instance"><SOAP-ENV:Body> <m:getStateName xmlns:m="http://www.soapware.org/"> <statenum xsi:type="xsd:int">41</statenum> </m:getStateName> </SOAP-ENV:Body> </SOAP-ENV:Envelope>


An HTTP request that carries a SOAP RPC responsesource: (http://www.soaprpc.com/tutorials/) A Busy Developer’s Guide To Soap1.1

HTTP/1.1 200 OKConnection: closeContent-Length: 499Content-Type: text/xml; charset=utf-8Date: Wed, 28 Mar 2001 05:05:04 GMTServer: UserLand Frontier/7.0-WinNT

<?xml version="1.0"?><SOAP-ENV:Envelope SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/" xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsd="http://www.w3.org/1999/XMLSchema" xmlns:xsi="http://www.w3.org/1999/XMLSchema-instance"> <SOAP-ENV:Body> <m:getStateNameResponse xmlns:m="http://www.soapware.org/"> <Result xsi:type="xsd:string">South Dakota</Result> </m:getStateNameResponse> </SOAP-ENV:Body> </SOAP-ENV:Envelope>


Error Examplesource: (http://www.soaprpc.com/tutorials/) A Busy Developer’s Guide To Soap1.1

HTTP/1.1 500 Server ErrorConnection: closeContent-Length: 511Content-Type: text/xml; charset=utf-8Date: Wed, 28 Mar 2001 05:06:32 GMTServer: UserLand Frontier/7.0-WinNT

<?xml version="1.0"?><SOAP-ENV:Envelope SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsd="http://www.w3.org/1999/XMLSchema" xmlns:xsi="http://www.w3.org/1999/XMLSchema-instance"> <SOAP-ENV:Body> <SOAP-ENV:Fault> <faultcode>SOAP-ENV:Client</faultcode> <faultstring>Can't call getStateName because there are too many parameters.</faultstring> </SOAP-ENV:Fault> </SOAP-ENV:Body> </SOAP-ENV:Envelope>


SOAP Packagessource: http://www.soapuser.com

Apache SOAP for Java

Apache Axis for Java

Idoox WASP for C++

Microsoft SOAP Toolkit (part of the .net framework)

SOAP::Lite for Perl


Apache SOAP

Allows clients and services to be written in Java

Part of the Apache-XML project (http://xml.apache.org/)

SOAP package downloadable: http://xml.apache.org/dist/soap/

Installation instruction:

http://www.xmethods.com/gettingstarted/apache.html


Apache SOAP installation

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Classpath setting

set CLASSPATH=C:\soap\soap-2_2\lib\xerces.jar;

C:\jdk1.3\bin;

C:\jdk1.3\lib\tools.jar;

C:\soap\soap-2_2\lib\mail.jar;

C:\soap\soap-2_2\lib\soap.jar;

C:\soap\soap-2_2\lib\activation.jar;

C:\tomcat\lib\servlet.jar;

.;


Writing a Client Application using Apache SOAPsource: http://www.xmethods.com/gettingstarted/apache.html

Classpath Your CLASSPATH environment variable should have both the "soap.jar" and "xerces.jar" JAR files included. Importing packages For basic SOAP method invocation, you should import the following at minimum:

// Required due to use of URL class , required by Call class import java.net.*;

// Required due to use of Vector class import java.util.*;

// Apache SOAP classes used by client import org.apache.soap.util.xml.*; import org.apache.soap.*; import org.apache.soap.rpc.*;


Ready-made SOAP ServicesA number of SOAP ready-made services are available at http://www.xmethods.com/

XMethods Service Weather Temperature

ID8

Service Owner:xmethods.net

Contact Email:[email protected]

Service Description:Current temperature in a given U.S. zipcode region.

SOAP Implementation:Apache SOAP


Sample SOAP service

An aly ze W S D L | View R P C P r o f ile | h t tp :/ /w w w .x m eth o d s .n e t /s d /2 0 0 1 /T em p era tu r eS erv ic e .w s d lX M eth o d s I D 8S er v ic e O w n er : x m eth o d s .n e tC o n tac t Em ail: s u p p o r t@ x m eth o d s .n e tS er v ic e Ho m e P ag e:D es c r ip tio n : C u r r en t tem p era tu r e in a g iv en U.S . z ip c o d e r eg io n .S O AP Im p lem en ta tio n : Ap ac h e S O AP

W e a the r - T e m p e ra tu re

Found at http://www.xmethods.com


RPC Profile for Service

R PC Pro f ile fo r S e rv ice " W e a th e r - Te m pe ra tu re "

M e th o d Na m e g e tTe m pEn dpo in t UR L h t tp: //s e rv ice s .x m e th o ds .n e t :8 0 /s o a p/s e rv le t /rpcro u te rS O A PA ct io nM e th o d Na m e s pa ce UR I u rn :x m e th o ds -Te m pe ra tu reI n pu t Pa ra m e te rs z ip c o d e s t rin g

O u tpu t Pa ra m e te rs r e tu r n f lo a t

See sample: TempClient.java


Client program samples

See samples in client folder:– TempClient.java– StockQuoteClient.java– CurrencyClient.java


SOAP data typesSOAP Data Types,

http://www.sdc.iup.edu/outreach/spring2002/webservices/datatypes.htmlUses XML Schema data typesPrimitive Typesstring, boolean, decimal, float, double, duration, dateTime, time, date, gYearMonth, gYear, gMonthDay, gDay, gMonth, hexBinary, base64Binary, anyURI, QName, NOTATION


SOAP data typesDerived Types

Simple types (derived from a single primitive type)* integer is derived from decimal* int (-2147483648 <= int <= 2147483647) is derived from long which is derived from integer * 5-digit zip code can be derived from int* may use regular expressions to specify derived types, such as ([A-Z]){2,3}-\d{5}


Complex Type

Complex types (struct or array)Struct example

<instructor> <firstname xsi:type="xsd:string">Ed</firstname>

<lastname xsi:type="xsd:string">Donley</lastname> </instructor>

Array example <mathcourses xsi:type=

"SOAP-ENC:Array" SOAP ENC:arrayType="se:string[3]"> <se:string>10452C</se:string> <se:string>10454C</se:string> <se:string>11123T</se:string>

</mathcourses>


Creating Web Services (server-side SOAP)

O'Reilly Network: Using SOAP with Tomcat [Feb. 27, 2002] http://www.onjava.com/pub/a/onjava/2002/02/27/tomcat.htmApache SOAP allows you to create and deploy a SOAP web service.You must install some .jar files on your system and set the CLASSPATH to them:

Algorithm:1. Write a class for providing the service.2. Create a deployment descriptor in XML.3. Deploy the service with the service manager.


The Apache SOAP service manager

The service manager is itself implemented as a SOAP service.

To see what services are deployed on your system:

java org.apache.soap.server.ServiceManagerClient http://localhost:8080/soap/servlet/rpcrouter list

To deploy a service:

java org.apache.soap.server.ServiceManagerClient http://localhost:8080/soap/servlet/rpcrouter deploy foo.xml


Creating a SOAP ServiceO'Reilly Network: Using SOAP with Tomcat [Feb. 27, 2002]http://www.onjava.com/pub/a/onjava/2002/02/27/tomcat.html

A SOAP service can be just about any Java class that exposes public methods for invocation. The class does not need to know anything about SOAP, or even that it is being executed as a SOAP service. The method parameters of a SOAP service must be serializable. The available types that can be used as SOAP service parameters are shown in (Listing 2) (shown on next slide)


SOAP Service Parameter TypesAll Java primitive types and their corresponding wrapper classes

Java arrays

java.lang.String

java.util.Date

java.util.GregorianCalendar

java.util.Vector

java.util.Hashtable

java.util.Map


SOAP Service Parameter Typesjava.math.BigDecimal javax.mail.internet.MimeBodyPart

java.io.InputStream

javax.activation.DataSource

javax.activation.DataHandler

org.apache.soap.util.xml.QName

org.apache.soap.rpc.Parameter

java.lang.Object (must be a JavaBean)


Sample SOAP Service Implementations

See sample in SOAP folder:

TempService: A temperature service

Exchange: currency exchange service and client


Sample SOAP Service Class// A sample SOAP service class// source: http://www.onjava.com/pub/a/onjava/2002/02/27/tomcat.html

package onjava;public class CalcService { public int add(int p1, int p2) { return p1 + p2; }

public int subtract(int p1, int p2) {

return p1 - p2; }}


Deployment Descriptor<isd:service xmlns:isd="http://xml.apache.org/xml-

soap/deployment" id="urn:onjavaserver"> <isd:provider type="java" scope="Application" methods="add subtract"> <isd:java class="onjava.CalcService"/> </isd:provider>

<isd:faultListener>org.apache.soap.server.DOMFaultListener</isd:faultListener>

</isd:service>


SummarySOAP is a protocol that makes use of HTTP requests and responses to effect remote method calls to web services.

A SOAP method call is encoded in XML and is embedded in an HTTP request

The return value of a method call is likewise embedded and encoded in an HTTP response

A number of SOAP APIs are available for programming web services and client method calls. The Apache API was introduced.

web services

Technology

soap soap

http request

soap messages

apache soap source

examples http

soap packages source

apache soap installation

http wired services